A UMTS typically includes a radio access network, referred to as a UMTS terrestrial radio access network (UTRAN). The UTRAN may interface with a variety of separate core networks (CN). The core networks in turn may communicate with other external networks (ISDN/PSDN, etc.) to pass information to and from a plurality of wireless users, or user equipments (UEs), that are served by radio network controllers (RNCs) and base transceiver stations (BTSs, also referred to as Node Bs), within the UTRAN, for example.
Development of UMTS as well as the releases of the CDMA2000 family of standards, and other 3rd generation wireless standards, has focused in part on enhancing the reverse or up link (UE to Node B) operation to support high-speed packet data applications. Currently, two types of modes or methods for scheduling UE transmissions are envisioned by these standards: a time and rate scheduled mode (also called a scheduled transmission mode) and an autonomous mode (also called a rate control scheduling mode).
The time and rate scheduled method schedules transmissions by having the Node B send a schedule grant message with an explicit instruction for the user equipment (UE) to transmit. A grant for a scheduled transmission designates the UE that is to transmit as well as the transmission format (data rate, frame/packet duration, and transmission power) the UE is to employ. The rate of a transmission is the number of information bits that constitute the transmission divided by the time interval over which the bits are sent.
The autonomous method on the other hand provides a looser form of control on UE transmissions. Here, the RNC via the Node B or the NodeB acting without the RNC sends a rate control directive or instruction, which is typically a one bit transmission, that can be either broadcast to all UEs in the cell/sector (common rate control) or transmitted individually to UEs (dedicated rate control). The rate control bit has a predefined meaning. For example, according to one proposal the rate control bit indicates whether the UE is to transmit at a predetermined rate limit or not transmit at all. The non-zero rate limit is signaled via an actual transmission to the UE while the zero rate limit is signaled by the Node B transmitter's silence. According to another proposal, the rate control bit indicates whether the UE is to transmit at an increased or decreased rate limit. As a further example, such as when the rate control method is being used to affect multiple UEs, the rate control bit(s) probabilistically influences the rate limit.